Stormwater Discharges from Municipal Sources in Region 10

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General Information

Under the National Pollutant Discharge Elimination System (NPDES) stormwater program, operators of large, medium and regulated small municipal separate storm sewer systems (MS4s) require authorization to discharge pollutants under an NPDES permit.

In Region 10, EPA is the NPDES stormwater permitting authority for facilities on Indian Country lands in Idaho, Oregon and Washington; and federal operators in Washington.

If EPA is not the permitting authority for your facility, contact your state's stormwater program:

• Alaska MS4 Program
• Idaho Stormwater Permits
• Oregon Municipal Stormwater Permits
• Washington Stormwater General Permits

For more information, visit:

• NPDES Stormwater Program in Region 10
• NPDES Stormwater Final MS4 General Permit Remand Rule

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MS4 Permits in Washington

EPA Region 10 is the NPDES permitting authority for MS4 discharges operated by federal entities in Washington, regulated MS4s located in Indian Country, and/or regulated MS4s discharging to waters subject to tribal water quality standards.

If your facility is not within one of these categories, visit Washington Stormwater General Permits for permitting information.

MS4 Permits for Areas of Washington under Federal and Tribal Jurisdiction

Facility or Permit Name	Permit Number	Effective Date	Expiration Date
Joint Base Lewis-McChord MS4	WAS026638	12-25-2013	09-30-2018
Naval Station Everett MS4	WAS026620	02-01-2021	01-31-2026
Naval Base Kitsap MS4	WAS026646	02-01-2021	01-31-2026
Naval Air Station Whidbey Island MS4	WAS026611	02-01-2021	01-31-2026
City of Tacoma MS4 Discharges to Puyallup Tribal Waters	WAS026680	Draft	N/A
Pierce County MS4 Discharges to Puyallup Tribal Waters	WAS026875	Draft	N/A
Washington State Department of Transportation MS4 Discharges to Puyallup Tribal Waters	WAS026743	Draft	N/A
Tulalip Tribes MS4	WAS026654	N/A	N/A